BELFAST, Northern Ireland  Police said 16 officers have been injured in street clashes after about 1,000 Protestants marched on Belfast City Hall to protest its decision to reduce displays of the British flag.

Violence broke out Saturday as Protestants passed Short Strand, the only Irish Catholic enclave in east Belfast. Masked, hooded Catholic youths tossed bottles, rocks and other makeshift weapons at the protesters. A running street battle ensued with heavily armored police in the middle.

Amid chaotic scenes, police used water cannons, shields and occasional shots of plastic bullets to force the Protestants away from the Catholic district.

Protestant extremists have mounted illegal protests and road blockades for the past six weeks in protest at Catholic council members’ decision to fly the flag only 18 days annually, not year round.